THE UTILIZATION OF EXPLOSIVE LOADING AS A NONDESTRUCTIVE EVALUATION TOOL IN GEOLOGIC MATERIALS

This paper describes the use of a small explosive charge to evaluate g eologic material in a non-destructive manner. One-dimensional computat ions have been performed using the Lagrangian finite difference code W ONDY to investigate the effects that open joints and weak layers of un consolidated material have on the propagation of stress waves resultin g from the detonation of an explosive charge. Data from testing conduc ted by others in models or in full scale in a number of different mate rials have been collected and examined. Several findings of importance were noted. The computational results indicate that the characteristi cs of a stress pulse after passing through an open joint are significa ntly different from those of a stress pulse that has passed through a weak layer. The examination of data from various explosive tests in di fferent media has yielded a way of determining the type of material th at the stress pulse has passed through. These preliminary results indi cate that it is theoretically possible to excite a geologic medium wit h a small explosive pulse and determine the type of rock and the exten t to which it contains either open joints or weak layers of unconsolid ated material.